When Physical is Not Real Enough

This position paper argues that policies for physical memory management and for memory power mode control should be relocated to the system software of a programmable memory management controller (MMC). Similarly to the mapping of virtual to physical addresses done by an MMU of a processor, this controller offers another level of mapping from physical addresses to real addresses in a multi-bank multi-technology (DRAM, MRAM, FLASH) memory system. Furthermore, the programmable memory controller is responsible for the allocation and migration of memory according to power and performance demands.
Our approach dissociates the aspects of memory protection and sharing from the aspect of energy-aware management of real memory. In this way, legacy operating systems do not have to be extended to reduce memory power dissipation, and power-aware memory is no longer limited to CPUs with an MMU.